Rheological measurements applications

C.W. Mackosko, Rheology, Principles, Measurements, Applications, Wiley-VCH, New York, 1994. 

Unfortunately the high Peclet number regime is where many rheological measurements are most easily made. High stresses and strain rates allow the development of simpler instrumental designs and lower sensitivities are required. It is also important to be aware of the fact that many applications require very high deformation regimes and it is... 

Fig. 4.20 Temperature dependence of the average relaxation times of PIB results from rheological measurements [34] dashed-dotted line), the structural relaxation as measured by NSE at Qmax (empty circle [125] and empty square), the collective time at 0.4 A empty triangle), the time corresponding to the self-motion at Q ax empty diamond),NMR dotted line [136]), and the application of the Allegra and Ganazzoli model to the single chain dynamic structure factor in the bulk (filled triangle) and in solution (filled diamond) [186]. Solid lines show Arrhenius fitting curves. Dashed line is the extrapolation of the Arrhenius-like dependence of the -relaxation as observed by dielectric spectroscopy [125]. (Reprinted with permission from [187]. Copyright 2003 Elsevier)...

In the event that the film is not rigid, the EQCM response is a function of both the film mass and its rheological characteristics. Application of the Sauerbrey equation under these circumstances is inappropriate it underestimates the mass change, to an extent that is dependent on the viscoelastic properties of the film. Under these circumstances, there are two questions to be addressed first, how does one diagnose film (non-)rigidity and, second, how does one interpret responses from a non-rigid film The answers to both questions can be found from crystal impedance measurements. This is a technique in which one determines the admittance (or impedance) of the loaded crystal as a function of frequency in the vicinity of resonance. Effectively, one determines the shape (width and height) and position (on the frequency axis) of the resonance, rather than just its position (as in the simple EQCM technique). 

Ultrasound measurement will undoubtedly be used in the future in the dairy industry. However, it is not yet fully clear which applications are likely to be important. Some manufacturers claim that rheological measurements... 

The application of low shear rheological measurements were the outcome of a joint research project between ICI Plant protection Division (Th. F. Tadros) and Bristol University (Prof. R. H. Ottewill, Dr G J Goodwin and Dr R Buscall). The authors are grateful to the Bristol group for establishing these techniques and their application to model suspensions. 

The viscosity of Newtonian and non-Newtonian materials increases exponentially with an increase in pressure. However, these changes are extremely small, and under atmospheric conditions of lbar, they are hardly detectable. Hence, the pressure is normally not controlled during rheological measurements. In some circumstances, the pressure exerted on, for example, oils and lubricants, can take up values in excess of 1 GPa (oil rigs, lubricants in gears), and the increase in viscosity is substantial. In such applications, it is thus required to consider the pressure as a factor when studying their rheological properties. 

Kang, K. Lee, L.J. Koelling, K.W. High shear microfluidics and its application in rheological measurements. Experiments in Fluids 2005, 38, 222-232. 

X-ray diffraction (XRD), transmission electron microscope (TEM), and rheological measurements are discussed. Third, the static and dynamic structures of confined polymer in the gallery are examined. Finally, the commercial applications for the PCNs are given. 

It is not possible in this chapter to do more than give a brief review of the subject and to indicate in rather general terms the way in which rheological measurements can help us to understand the behaviour of colloids. Some of the technological applications of rheological properties will be dealt with in Chapter 14. 

Navarrete R.C. 1991. Rheology and Structure of Hocculated Suspensions. [CWM, LES] Chen K.S.A. 1992. Studies of Multilayer Slide Coating and Related Processes. [LES] Cai J.J. 1993. Coating Rheology Measurements, Modeling and Applications. [CWM, LES] Benjamin D.F. 1994. Roll Coating Flows and Multiple Roll Systems. [LES]... 

Rheological measurements were carried out using a capillary viscometer and the studies were conducted with and without application of nltrasonic oscillation. The results obtained are shown in Figure 5.3 and indicate the dependence of the effective flow state (p f on the stress shear. The definition of the toughness depends on the arguments about the influence of the ultrasonic oscillations using the expression ... 

The rheological properties of adhesives and sealants are important in many applications. When these products must be pumped or applied through automated equipment, the flow characteristics at pertinent shear rates are critical. Sophisticated rheological measurements can be performed to predict performance. The rheology of silicone adhesives and sealants can be tailored through adjustment of polymer viscosity, filler loading, and incorporation of various additives. 

Equation (3.41) can now be used directly to give the pressine drop for any pipe diameter if the flow is turbulent. Alternatively, this approach can be used to construct a wall shear stress (T )-apparent wall shear rate (SV/D) turbulent flow line for any pipe diameter. This method is particularly suitable when either the basic rheological measurements for laminar flow are not available or it is not possible to obtain a satisfactory lit of such data. The application of this method is illustrated in example 3.8. 

Non-Newtonian liquids are used in numerous microfluidics applications, including microscale viscosity and rheology measurements, amplification and sequencing of DNA, fundamental investigations of elastic flows, and development of fluidic memory and control devices. Although these applications span a wide range of flow conditions and non-Newtonian fluid properties, similar experimental methods are used. In this section we summarize some of the experimental... 

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